But there may have been another form of such tongs, like the letter X, or two such figures combined; and by increasing the series we should produce the instrument known as the lazy-tongs, which collapse into a very small space, yet will extend to a great distance. 50. A complete light portable Ladder, which taken out of ones Pocket, may be by himself fastened an hundred foot[4] high to get up by from the ground. Footnote [4] feet. P. [_A Pocket-ladder._] There are many curious and ingenious designs for portable scaling ladders, offered by Vegetius in “De re militari,” 1535, but which would require to be very considerably modified to become pocketable; however, they occur in every variety at page 35, in short pieces, each with a screw at one end, and a socket at the other; at p. 59, as a neat rope ladder; at p. 113, on the principle of the lazy-tongs; and at p. 162, a method of connecting short poles is exhibited. Robert Fludd, in the second book of his works, published in 1617 and 1618, folio, Page 384, gives a large copper-plate engraving of a very ingenious form of ladder. Each step is of wood, and the two sides of rope. The ingenuity of the invention consists in each step having a ferrule at one end, and the opposite end tapered sufficiently to fit into each ferrule of the adjoining step; by this means the whole can be put together like an ordinary fishing rod, and the top step terminating with a hook, it can easily be attached to any elevated place, and on pulling the pole, each part separates, falling at once into the form of a ladder with rope sides. Bourne’s 62nd Device, in his “Inventions, or Devices,” 1578, is--“How for to make a scaling ladder.” Van Etten, 1653, gives for his 111th Problem, “To make a Ladder of Cords, which may be carried in ones pocket: by which one may easily mount up a wall, or tree alone.” It consists simply of two pulleys, with “a cord of an half inch thick (which may be of silk, because it is for the pocket),” having a staff at one end to sit upon. The author gravely concludes, “This secret is most excellent in warre, and for lovers, its supportablenesse avoids suspition.” See page 248. Among Friar Bacon’s inventions, the following is recorded in the fourth chapter of his “Discovery of the Miracles of Art, Nature and Magick,” 12mo. published in 1659:--“It is possible to invent an Engine of a little bulk, yet of great efficacy, either to the depressing or elevation of the very greatest weight; which would be of much consequence in several accidents; for hereby a man may either ascend or descend any walls, delivering himself or comrades from prison; and this engine is only three fingers high and four broad.” 51. A Rule of Gradation, which with ease and method reduceth all things to a private correspondence, most useful for secret Intelligence.